For various reasons it is often desired to lower the surface tension of aqueous liquids. For example, by lowering the surface tension of aqueous liquids, solid matter can be more easily wet by the liquid. This property is useful, for example, when treating subterranean formations with various aqueous liquids to stimulate the flow of petroleum and/or aqueous fluids therefrom. Thus, it is desirable to, for example, employ acidizing, hydraulic fracturing, and other aqueous treatment liquids having low surface tensions.
Low surface tension values in combination with the water wetting properties of an aqueous liquid reduce the capillary forces in the formation being treated. Reduction of the capillary forces in a reservoir results in a more effective recovery of fluids after the formation has been treated. The present invention concerns the discovery of a composition which, when added to an aqueous liquid, effectively reduces the surface tension thereof and also increases the water wetting properties of the liquid.
Various quaternized perfluoroalkane-sulfona-midopolymethylenealkylamine compounds are known to reduce the surface tension of neutral, acidic and basic aqueous solutions even when present in minute amounts (see U.S. Pat. No. 2,759,019). However, these compounds were found to become ineffective when the aqueous solution in which they were employed came into contact with earthen formations. Thus, the use of such compounds in liquids employed to treat, for example, subterranean formations is limited. The present invention concerns the discovery of how to effectively make use of the surface active properties of such compounds in these types of liquids.